The present invention relates to an apparatus for winding parallel strips of material, such as metal strips, onto a drum.
Thin strips of material, such as steel, may be formed by slitting a wide web of material into a number of thin strips. For purposes of storage and shipping convenience, these thin strips of material may be wound onto a drum immediately following the slitting process. FIG. 1 shows three thin strips 20 of material, which have been slit downstream from a continuous web of material (not shown), being wound onto a drum 100 to form separate reels of thin strip material.
Because all thin strips 20 of material wound onto the drum 100 originate from the same wide web of material, it is desirable for all of the strips to be wound onto the drum at the same rate. If the strips 20 are not wound at the same rate, one of two conditions may occur. Winding a strip 20 at a rate that is slower than that of another reel on the drum may produce slack in the more slowly wound strip. Such slack may cause the strip 20 to be wound more loosely than is desired, and result in a drum with nonuniform reels of wound material. In extreme cases, such slack may accumulate to the point that it drags on the floor, or requires the creation of a large pit for accommodation of the slack. Alternatively, winding a strip 20 at a higher rate than other reels may produce excess tension in the more quickly wound strip. This tension may cause the strip to be wound too tightly, or in extreme situations cause damage to the strip or the apparatus used for the winding operation.
One hypothetical method of ensuring that all the strips are wound on a drum with uniform tension and at a uniform speed would be to make sure that all of the reels have the same thickness xe2x80x9cdxe2x80x9d throughout the winding process. Reels with the same thickness inherently take up thin strip material at the same speed. As shown in FIG. 1, however, it is not uncommon for the neighboring reels of thin strip material to have different thickness xe2x80x9cd.xe2x80x9d The production of reels with different thicknesses on the same drum may occur as a result of any of the following in isolation or combination: uneven wide web thickness, uneven coating thickness on the wide web, excessive/uneven burr on the wound strips, a loose leading strip edge, uneven applications of slitting lubricant, etc. Thus, it is not uncommon for the xe2x80x9cnaturalxe2x80x9d rate of strip take up to be different for the various reels on a drum.
It has been determined, however, that the xe2x80x9cnaturalxe2x80x9d rate of strip take up for each individual reel of strip material may be modified by providing for slip between the reel and the drum on which it is wound. In other words, the rate of take up of each individual strip may be controlled.
One known method of controlling the take up speed of each strip on a drum is described in, Lofstrom, Roger J., The Benefits and Limitations of Coreslip Rewinding, The Fabricator, October 1995, which is incorporated by reference herein. The afore noted article describes a Coreslip rewinding system in which the winding drum includes a number of outer drive rings on its outer surface. Each thin strip of material may be wound onto a separate drive ring. The drive rings may be made of plastic material, which provides them with the ability to slip relative to each other and the drum that drives them. The amount of xe2x80x9cslipxe2x80x9d of the drive rings is adjusted by adjusting the lateral pressure applied to the rings. The tighter the drive rings are squeezed together, the greater the friction between them, and the less they slip. By selectively adjusting the lateral pressure applied to the rings, the relative slip may be set so that each thin strip of material is wound under a relatively uniform tension.
While the foregoing Coreslip device provides the needed slip between adjacent reels, it does so at a cost. The plastic drive rings are susceptible to wear and heat, and may need to be changed frequently, raising cost and maintenance concerns. Furthermore, because each strip of material is subjected to the same amount of tension force, the strips must be of comparable width to avoid excessive loading of narrower strips.
Another known method of controlling strip take up speed is described in Lofstrom, U.S. Pat. No. 5,292,084 (Mar. 8, 1994). The Lofstrom patent discloses a core slip rewinding system in which each individual strip is wound over a series of roller bearings. The roller bearings underlying each reel are free to rotate independent of the neighboring roller bearings of other reels. As such this system may be capable of reducing the friction between the reels and the drum to near zero levels. Although this system may be very effective, it suffers from being relatively expensive to manufacture compared to alternatives. Furthermore, such a system can only accommodate one size of drum.
Upon study of the foregoing Lofstrom devices, it became apparent to the present Applicant that a preferable winding apparatus would provide near zero friction between the wound material and the core on which it is wound. Any friction that is needed to control the amount of slip between the wound material and the core may be provided by laterally squeezing the strips of wound material together. By limiting the friction providing component to one parameter, precise control may be exercised over the amount of relative slip between the strips of wound material. While the later Lofstrom device provides the low friction required, it does so at the cost of monetary expense and limited versatility.
Therefore, there is a need for a method and apparatus for winding strip material that is more economical to produce and maintain than previously known systems. There is also a need for a method and apparatus for winding that is easier to operate, able to accommodate a wider selection of drum sizes, and does not require a slack pit. There is also a need for such a system that provides improved control over the relative slip between strips of wound material using lateral pressure.
In response to these needs, the present applicant has developed a method and apparatus for winding strip material on a drum which differs from the systems described above. In a first embodiment of the applicant""s invention, a cushion of fluid, preferably air, may be selectively provided between the winding drum and the strip material wound thereon to reduce the friction there between.
It is therefore an object of the present invention to provide a method and apparatus for reducing friction and/or controlling the amount of friction between a winding drum and the material wound thereon or therearound.
It is another object of the present invention to provide a method and apparatus for selectively adjusting the amount of slip between a winding drum and a reel of wound material.
It is still another object of the present invention to provide a method and apparatus for reducing friction and/or controlling the amount of friction between individual strips of material wound on a winding drum.
It is yet another object of the present invention to provide a method and apparatus for winding strip material that is more economical than previous methods and apparatuses.
It is still yet another object of the present invention to provide a method and apparatus for winding strip material that requires less maintenance than previous methods and apparatuses.
It is still another object of the present invention to provide a method and apparatus for winding strip material that can accommodate different sized winding drums.
It is still another object of the present invention to provide a method and apparatus for supplying a bed of pressurized fluid between the outer surface of a winding drum and material wound thereon.
It is still yet another object of the present invention to provide a method and apparatus for controlling the pressure of a fluid provided between the outer surface of a winding drum and material wound thereon.
Additional objects and advantages of the invention are set forth, in part, in the description which follows, and, in part, will be apparent to one of ordinary skill in the art from the description and/or from the practice of the invention.
In response to the foregoing challenges, applicant has developed an innovative apparatus for winding strips of material comprising: a drum adapted to rotate about a longitudinal axis, said drum having a winding surface; a plurality of openings provided in the drum winding surface; and a means for supplying pressurized fluid to the openings.
Applicant has further developed an innovative apparatus for winding strips of material fed to the apparatus from a slitting machine, said apparatus comprising: a rotary arbor; a drum having an interior and a winding surface, said drum removably mounted on the rotary arbor; a plurality of openings providing communication between the drum interior and the drum winding surface; a pressurized fluid source; and at least one pressurized fluid passage connecting the pressurized fluid source to the openings.
Applicant has still further developed an innovative method of controlling the amount of friction between the winding surface of a drum and a plurality of material strips wound around said drum, said method comprising the steps of: providing a core insert around the drum winding surface; winding a strip of material around the core insert; and providing fluid between the winding surface and the core insert.
Applicant has still yet further developed an innovative method of reducing the amount of friction between the winding surface of a drum and a plurality of material strands wound around said drum, said method comprising the steps of: winding at least two strands of material around the drum winding surface; and supplying above ambient pressurized fluid to the winding surface.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated herein by reference and which constitute a part of this specification, illustrate certain embodiments of the invention, and together with the detailed description serve to explain the principles of the present invention.